KR20100106418A - System and method for playback of partially available multimedia content - Google Patents

Abstract

When the main information or the playback data is included in the media file, even if only a part of the multimedia content is partially available, the multimedia content can be decoded and presented.

Description

SYSTEM AND METHOD FOR PLAYBACK OF PARTIALLY AVAILABLE MULTIMEDIA CONTENT}

The present invention generally relates to a multimedia file, and more particularly to a multimedia file that can be played when only a portion of the multimedia file is available.

The Internet revolution has brought about a fundamental change in the distribution of information in the world. The collection and distribution of knowledge among users has gone through a basic paradigm shift, so that encyclopedias written collectively are commonly used as video-sharing and downloading services. The ability to easily exchange information has also paved the way for the distribution of multimedia content on the Internet. This distribution may occur through many methods, including but not limited to direct download from a server, server-managed content distribution, or via a peer-to-peer torrent network. Can be.

Recently, certain advances in the download strategy for content distribution have led to a system that enables piecewise downloading of multimedia files, which can later be gathered back to provide the finished file in the correct order of bytes. Case-by-case downloading can obtain data from multiple, concurrently existing sources, and possibly also help speed up the download of the entire file. By case-by-case downloading, there is generally no foreseeable pattern for delivering different file segments, and the size of the downloaded cases is not or can be verified.

Typically, multimedia files comprise a particular section, such as a header, media data or payload, and an indexing section, which may be optional. Typically, the header section contains a technical description of the media data, and without the header section, the media data cannot be decoded and played back. Typically, the indexing zone contains information describing the location of the media data in the file, allowing for random searching during playback. In addition, if the media data zone contains any errors, the data in the indexing zone provides a way in which the next error-free media data chunk can be located, so that the indexing zone can provide some error tolerance. have.

Some files may utilize distributing means that surround the information contained in each of these zones, while it is much easier for certain information related to decryption to be collected in one particular segment of the file. For example, in many different container formats, the header section is arranged as single contiguous blocks of data at the front-end of the file. Therefore, the particular segmentation of the key information required to decrypt the multimedia presentation may mean that the file cannot be successfully decrypted until the file is reconstructed as a whole.

Systems and methods are described that allow multimedia content to be decoded and presented by only partially available multimedia content that includes key information or playback data.

In one embodiment, a method of playing a partially provided multimedia file comprises: reading a portion of a partially provided multimedia file comprising content data having a plurality of media frames; Identifying a critical information chunk within a plurality of chunks in a media data zone, the critical information chunk deciphering the content data without obtaining additional portions of the partially provided multimedia file. An identification step comprising information for; Decrypting the content data based only on the identified primary information chunk; And presenting the decrypted content data.

In another embodiment, a method of encoding a partially provided multimedia file includes supplying content data from one or more sources; Incorporating main information before a key frame in the supplied content data; Repeating incorporation of one or more key frames in the supplied content data; And generating a multimedia file from the supplied content and embedded main information, wherein the main information includes information for decrypting the supplied content independently of other key frames or other portions of the supplied content. Include.

In yet another embodiment, a system for playing partially provided media files includes a media server and a client processor. The media server is configured to deliver the corresponding partially provided media file with key information adjacent to one or more key-frames of the media content in the partially provided media file. The client processor in network communication with the media server is configured to send a request for the partially provided media file to the media server, wherein the media server is configured to deliver the requested partially provided media file. The client processor includes a playback engine configured to locate the primary information and to independently decrypt the partially provided media file based on the located primary information.

These and other features of the present invention and methods of obtaining and using them will become more apparent and will be best understood by reference to the following description taken in conjunction with the accompanying drawings. The drawings illustrate only typical embodiments of the invention and thus do not limit the scope of the invention.

1 is a semi-schematic illustration of a network for downloading multimedia files in accordance with one embodiment of the present invention;
2 is a conceptual illustration of a partially downloaded multimedia file;
3 is a conceptual illustration of information tracks interleaved with multimedia information in a multimedia file in accordance with one embodiment of the present invention;
4 is a conceptual illustration of a multimedia file with major information chunks in accordance with an embodiment of the present invention.

Turning now to the drawings, a system for gradually assembling and playing multimedia files and remotely stored multimedia files is described. Multimedia files can be assembled gradually from one or many sources, and different pieces are used to build up the entire file over time. In many embodiments of the present invention, key information or playback data required by the player to initiate playback of content in a multimedia file is repeated at various locations throughout the file. This main information is the information used by the player to decode the video, audio and other stream types in the file. For example, the main information may be, for example, but not limited to, information representing a video codec standard, information representing a voice codec standard, video resolution, voice sampling rate and / or a total channel ( total channel). In many embodiments, key information is repeated within the media data region of the file, adjacent to the access frame. In some embodiments, key information is included in the media data chunks in one or more or every access frame. In many embodiments, key information is included in information chunks interleaved within a media data area within a file such that each example of that key information is located adjacent one or more or every access frame. In some embodiments, key information provided in a multimedia file is different for more than one access frame and / or is not repeated for each access frame in the multimedia file. In many cases, key information is expressed at least in part for a predetermined set of profiles. In many embodiments, key information about conventional multimedia files is provided in a separate secondary file to facilitate playback of the multimedia file during gradual download. In yet another embodiment, the progressive download scheme implies the use of boundaries aligned with access frames in the multimedia file.

Configure for gradual download of multimedia files

A multimedia distribution network in accordance with one embodiment of the present invention is shown in FIG. The distribution network 10 comprises a number of devices configured as players 12. In the illustrated embodiment, the player is a personal computer and a mobile phone handset. In another embodiment, the player can be any device that can obtain multimedia information via a network connection and can reproduce the multimedia information. The player 12 may be connected to the server 14 via the network 16 and gradually download the multimedia file stored in the server. In many embodiments, the player is configured to download multimedia files from a single server. In many embodiments, the player is configured to download multimedia files from multiple servers simultaneously. In some embodiments, the player may utilize a multimedia file using a peer-to-peer file sharing application, such as a BitTorrent application, distributed by BitTorrent, Inc., San Francisco, California. Assemble gradually. In other embodiments, the player may use other applications that progressively download multimedia files from one or more servers.

Repetition of key information or playback data in multimedia files

A hypothetical construction of a multimedia file as gradually downloaded is illustrated in FIG. Different zones of the multimedia file 20 are illustrated separately. The multimedia file includes a header 22, a payload 24, and an index 26. Several hypothetical snapshots 28 of the cases of the file obtained by the player during the gradual download of the file over time are illustrated. The snapshots show the gradual completion of the gradual download of the multimedia file from 0% to 100%. If the multimedia file is gradually downloaded, there may be a significant waiting time between the start of the download and the point in time at which the entire header can be reconstructed by the player. This wait time is shown as a hypothetical download due to the fact that the header was not downloaded until the 14th snapshot in time. Because of this download pattern, a conventional multimedia file that had a significant proportion of its content downloaded may not be playable if the main part is placed in the header segment of the file. Also, if the header portion has never been downloaded by the receiver, the rest of the file may not be playable even if other portions of the file have been downloaded without error. In another embodiment, it is important to emphasize that the header portion of FIG. 2 can be replaced with any portion of the multimedia file containing the description needed to initiate playback of the audio and video streams.

In accordance with an embodiment of the present invention, a multimedia file includes key information at multiple locations through the file. As soon as the player gets the key information, the player has the ability to play the content in the multimedia file that has already been downloaded. In some embodiments, key information is paired with related multimedia information. Thus, the main information is downloaded as the multimedia information is downloaded. How the information is encoded and how often the main information is repeated through the multimedia file can be determined by the requirements of the particular application and / or the total amount of information needed to successfully decode the presentation.

Matching key information to access frame ( PAIRING )

In general, multimedia files have access frames that can be decrypted and presented independently, without the need for any previous or future information in the payload area. If the user instructs the player to play from a particular access frame, the player can play the content once downloaded, provided that the key information needed to successfully decode and present the multimedia data is available to the player. In many embodiments, key information is provided in connection with an access frame. In many embodiments, an access frame is contained within a container of a multimedia file and key information is represented within the header of that container. In other embodiments, key information may be represented at other locations within the multimedia file.

Individual information tracks

In accordance with several embodiments of the present invention, a multimedia file may include individual information tracks interleaved with the multimedia content in the file such that key information appears in one or more or immediately before or adjacent to each access frame. . In many embodiments, the information track includes a unique marker, which may be a few bits but is typically 4 to 16 bytes or more, and is uniquely identified with a moderately low likelihood of unintentional emulation in payload data. Can be. An information track is outlined above, containing a direct detail of the audio, video, subtitles and / or other streams followed by a portion of that information track containing key information and / or a reference to a predetermined profile. The main information can be expressed in a predetermined manner including those in the drawings.

A multimedia file containing an information track in accordance with an embodiment of the present invention is illustrated in FIG. 3. The multimedia file 30 includes interleaved multimedia information. Multimedia information may include, but is not limited to, video, audio, subtitles, and / or information tracks. The multimedia information includes a number of access frames 32. Information 34 from the information track is interleaved just before the access frame. In another embodiment, the information may involve an access frame. The information 34 includes key information used by the player to decrypt the access frame 32. In many embodiments, information 34 also includes other information regarding the decryption of the overall multimedia file.

In FIG. 4, the multimedia file according to an embodiment of the present invention further illustrates main information about the file. The multimedia file 40 includes an Extensible Binary Meta Language (EBML) element 41 and a segment element 42. Segment elements include: search head 43, segment information 44, tracks 45, chapters 46, one or more clusters 50, cues 47, attachments. (Attachments) 48 and Tags (49). Track 45 with one or more track entries includes information about each of audio, video, subtitles and / or other media tracks (eg, media data), i.e., playback data. Within the cluster 50, track information 51 may be located with one or more simple blocks 52 and / or one or more block groups 54. The simple block or block group may include audio, video, subtitles and / or other media frames. The simple block in one embodiment includes, for example, a key or access frame identifier 53 configured to identify a block with a key frame. The block group includes block (s) 55 similar to simple block 52 but using a lack of reference block value as a way of indicating that it is a key frame that is an included frame (ie, does not have any reference frame). . The block or blocks 55 in the illustrated case also includes the reference block 56, that is, the time code of another frame. As illustrated, the track information 51 includes double track information corresponding to the track information 45 in the segment element 42, the track 45 '. The track information provides all the necessary information, for example audio / video codec information, in order to play content or frames in the associated cluster. As such, each cluster, optionally including key-frames, may also have playback data or key information in the form of track information 51 to provide video, audio subtitles, and / or other tracks associated with a given cluster. The track information 51 may exist within each cluster containing key-frames, or may optionally appear at a lower frequency, such as occurring 10 or 20 times per file. A lower frequency than that can increase the seek time to find key information, but will also reduce the file size of the multimedia file. Thus, the key information may be one or more or every key-frame contiguous, the frequency of which may affect seek time and multimedia file size.

Representation of key information

Repetition of key information through a multimedia file increases the file overhead. In order to reduce the number of bits needed to represent the key information, encoding of a set of profiles can be established for the multimedia content, and the reference to the profile is multimedia as opposed to specifying all the key information multiple times throughout the file. Can be used within a file. In many embodiments, a profile is defined that includes a set of predetermined parameters for voice, video, subtitles, and other related data. As described above, in accordance with many embodiments of the present invention, a multimedia file includes profile references in containers that contain access frames and / or as data in separate information tracks. Predetermined parameters specified in the profile include, but are not limited to, video vertical / horizontal resolution, video frame rate, audio sampling rate, audio channel number, subtitle type, video codec type, audio codec type, and / or subtitle resolution. It may include. The selection for a particular profile may be performed via an indicator in the container surrounding the access frame.

In many embodiments, the multimedia file may directly specify key information of a certain aspect, and may provide a reference to a predetermined profile for another aspect of that key information. For example, the horizontal and vertical resolution for an image portion could be specified independently, while all other parameters are selected from a predetermined profile. In some embodiments, restrictions are imposed on independently specified parameters. For example, horizontal and vertical resolution may be limited for units of 4, 8, 16 or more pixels. The way in which references to directly specified parameters and / or predetermined profiles are encoded in a multimedia file according to an embodiment of the invention typically depends on the requirements of the particular application. Any of a variety of formats can be specified. The encoding typically involves balancing the ease of decoding with limiting the amount of overhead in the multimedia file.

Identification of access frames or key information during gradual download

In order to easily identify the access frames, these frames may have a stream identifier different from the stream identifier used to indicate a non-access frame. This stream identifier may be 4 bytes or more, and preconditioning requirements may be imposed for every individual frame in the payload region to begin on a 4-byte aligned boundary. This may facilitate searching for access frames, and may also reduce the likelihood that the stream markers will be imitated by payload data.

An application used to progressively download a multimedia file in accordance with an embodiment of the present invention has a utility that can be used to distribute the file over a network, including one or more of each access frame, or one or more or each major information chunk. It may be necessary to perform any data zone partitioning on the boundary aligned with the start. In this way, this segment starts with an access frame or key chunk of information, and the search operation in the decoder as well as a separate marker can be omitted.

Provision of Key Information in Secondary Files

In many embodiments, a player that gradually downloads a multimedia file may also specify the location of one or more or every access frame, or major chunk of information in the multimedia file, along with appropriate header and index information for the multimedia file. Get the car file. In this way, the secondary file can be obtained as a whole and used as a guide in the reproduction of a partial section of the multimedia file. In some embodiments, the secondary file is expected to be much smaller than the multimedia file, and as a result can be more easily obtained through a network-based distribution method. Secondary files may be particularly useful in applications where a large number of conventional multimedia files exist. The use of secondary files may be more desirable than re-encoding each of the existing multimedia files.

Although the above description includes many specific embodiments of the present invention, these should not be understood as limitations on the scope of the present invention, but rather should be understood as examples of one embodiment thereof. Accordingly, the scope of the invention needs to be determined not by the illustrated embodiments, but by the appended claims and their equivalents.

Claims (25)

Reading a portion of a partially provided multimedia file comprising content data having a plurality of media frames;
Identifying a critical information chunk within a plurality of chunks in a media data zone, wherein the critical information chunk decrypts the content data without obtaining additional portions of the partially provided media file. an identification step comprising information for decoding);
Decrypting the content data based only on the identified primary information chunk; And
Presenting the decoded content data. The method of claim 1, wherein the primary information chunk is a repetition of one or more or all media data track headers. 2. The method of claim 1, wherein the primary information chunk comprises a video codec identifier. 2. The method of claim 1, further comprising obtaining the primary chunk of information as a separate file from the partially provided multimedia file. The method of claim 1, further comprising placing a pointer in the primary information chunk. The method of claim 1, further comprising storing the identified primary information chunk. 7. The method of claim 6, further comprising retrieving the stored primary information chunk for one or more key-frames. The method of claim 1, wherein the primary information chunk is located adjacent one or more key-frames through the partially provided multimedia file. The method of claim 1, wherein the primary information chunk is different between one or more key-frames. The method of claim 1, wherein the information of the main information chunk specifies at least one of an image resolution, an image frame rate, an audio sampling rate, an audio channel number, a subtitle form, an image codec type, an audio codec type, and a subtitle resolution. A method of playing a partially provided multimedia file, based on a profile. Supplying content data from one or more sources;
Incorporating key information before the key-frame in the supplied content data;
Repeating incorporation of one or more key-frames in the supplied content data; And
Generating a multimedia file from the supplied content and embedded main information,
Wherein the main information includes information for decoding the supplied content independently of other key-frames or other portions of the supplied content. 12. The method of claim 11, wherein the main information includes at least one of a video codec identifier, a voice codec identifier, a video resolution, a voice sampling rate, and a voice total channel. 12. The method of claim 11, wherein the incorporation of the primary information is performed every key-frame. 12. The method of claim 11, further comprising: generating a primary information file that includes information for decrypting the supplied content that is different from the multimedia file and independent of other key-frames or other portions of the supplied content; Further comprising, wherein the incorporated main information is referencing the main information file. 12. The method of claim 11, wherein the primary information includes a track header of the supplied content. 12. The method of claim 11, wherein the primary information is different between one or more key-frames. 12. The method of claim 11, further comprising the step of incorporating a reference to a profile that provides reproduction information different from the embedded primary information. 12. The method of claim 11, wherein incorporating the key information further comprises incorporating the key information into a container header of one or more key-frames. 12. The method of claim 11, wherein the plurality of key frames in the supplied content data in the payload begin on a 4-byte aligned boundary. 12. The method of claim 11, wherein incorporating the main information further comprises encoding an information track having the main information and interleaving the information track into content data of the multimedia file. , Partly provided method of encoding a multimedia file. A media server configured to deliver a corresponding partially provided media file having key information adjacent to one or more key-frames of the media content in the partially provided media file; And
A client processor in network communication with the media server and further configured to send a request for the partially provided media file to the media server,
The media server is configured to deliver the requested partially provided media file, and the client processor is configured to locate the primary information and independently decrypt the partially provided media file based on the located primary information. A playback system of a partially provided multimedia file. 22. The system of claim 21, wherein the primary information includes at least one of a video codec identifier, a voice codec identifier, a video resolution, a voice sampling rate, and a voice total channel. 22. The system of claim 21, wherein the primary information includes a track header of the media content. 22. The system of claim 21, comprising locating a stream identifier representing a key-frame. 22. The media server of claim 21, wherein the media server delivers the partially provided media file in data partitions, each partition being aligned with the beginning of one or more key-frames or major information chunks. A playback system for partially provided multimedia files.

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